Spring-adjusting mechanism.



F. F. DORSEY.

SPRING ADJUSTINGMEGHANISM.

APPLIOATION HLBD MAR. l, 1912.

Patented Nov. 11, 1913 Lof/8,134;

UNTTED STATES PATENT onirica.

ramrmvrl E. no EsEY, or ROCHESTER, NEW YORK, Assrenon To SENECA CAMERA MANUFACTURING COMPANY,

0F ROCHESTER, NEW YORK.

. SPRING-ADJU'STING MEGHANISM,

Specification of Letters Patent.

Application filed March 13, 1912. Serial No. 683,637.

. State of New York, have invented certain new and useful Improvements in Spring- Adjusting Mechanism, of which the followinis a specification.

his invention relates to mechanism for adjusting the tension of a spring, and is particularly applicable to shutters of the roller-blind type, wherein spring-actuated rolle-rs are employed to actuate flexible curtains.

The object of the invention is to ,produce a tension-adjusting mechanism in which a single, rotary, manually-operable member may be employed both for the purpose of increasing the tension, and for the purpose of decreasing the tension, this member being manually' rotatedin one direction or the other according to the nature of the adjustment required, but being securely held, normally, against movement under the influence of the spring.

To the foregoing end I employ a construction in which .the detent, or means for retaining the manually-operable member and the spring in adjusted position, operates yieldingly, so that upon the application of a force slight-ly greater than the force of the spring the effect of the detent may be overcome, and the manually-operable member rotated in either direction. In the preferred embodiment of the invention I also employ a detent-mechanism of such form and construction that the resistance to rotation of the manually-operable member is comparatively slight when the latter is rotated in a direction to increase the tension of the spring, while against rotation in the opposite direction'the detent-mechanism opposes a greater resistance, suiiicient to effectually Overcome the tendency of the spring to rotate the member.

The invention will be more particularly set forth in the following description of the embodiment illustrated in the accompanying drawings, in which'- Figure 1 is. a side-elevation of parts of a roller-blind shutter embodying the present invention; Fig. 2 is a front-'elevation of the parts shown in Fig. 1, in section on the line 2,--2 in theplatter fig-ure; and Figs. 3 andx 4 are detail-views, on a larger scale, illustrating the operation of the cam and the detent-arm under different circumstances.

While my invention may be embodied inl roller-blind shutters of various types,`I have illustrated it, for convenience, as embodied. in a shutter such as that disclosed in the patent to Joseph Goddard, No. 1,009,501, granted November 21, 1911, and I'have, therefore,

Patented Nov. 11, 1913.V

shown in the drawings only so much of the shutter as is necessary for an understanding of the application thereto of the present invention. the illustrated. shutter has the usual iexible vcurtain 6, which is normally wound upon an upper roller 7 from which it is drawn in the production of an exposure, being rewound upon a spring-actuated roller 8 at the bottom of the mechanism. In passing from the roller 7 to the roller 8 the curtain is directed by guide-rollers 9 in the usual manner.

The spring-roller 8 is hollow, being constructed of a metal tube, and within it is inclosed a long helical spring 10, as is usual in such constructions, one end (not shown) of the spring` being fixed to the roller, while the other end is fixed, as shown in Fig. 2, to a shaft 11 which passes through the center of the roller.V The roller is provided at the end with a bushing 12, fixed to the tube and free to rotate upon the spring-shaft 1l. The

f shaft thus constitutes a bearing for the roller.

The shaft is normally stationary, but it passes loosely through a plate at the side of th'e shutter, and may be rotated in either direction, to increase or decrease the tension of the spring.

For the j )urpose of rotating the springshaft as just. described, the shaft is provided,

at itsouter end` with a milled head 125, as in said patent, this head constituting a manually1'c-.tabl e member which may be turned by` the thumbl and inrer. The head is screwed upon, the end of the shaft, and is also fixed in place by a set-screw let.

The novel features of the present invention reside in the vdetent-mechanism by which the head 13 and the spring-shaft are normally held againstrotation. To this end a cam 15 of oval or substantially elliptical form is fixed upon the inner end of the head 13,'and this cam is engaged by a Adetent-arm` 16 pivoted, at one end, upon a stud 17 Screwed into the plate 22. The other end As in the shutter of said patent, y

of the' detent-arm is connected with a spring. 18, of which the upper end is fixed to a pin 19 projecting from the plate 22.. The upper surface of the detent-arm 16 is curve l conform to the surface of the c'am, so that in the' normal position of the parts the arm rests closely against one of the long sides of the cam, as shown A in Fig. 1. The spring 10` tends to rotatethe spring-shaft and the cam in the directionof the arrow in Fig. l.: This tendencylis opposed, however, by 4the` pressure of the datent-arm4 against the cam, the

force of the spring 18 being suflicient' toI maintain the parts in the position'of Fig. 1. When it is desired to increase the tension of the spring 10, however, this may be readily 'done by rotating the` heath-and the parts connected therewith, in the direction of the arrow in Fig. 3. During thisoperation'the detentarm 1s swung downwardly, against thefresistance ofthe spring 18, by the rotation of the cam, but as the high points of the cam first engage the arm, at this time, near its free endas shown in Fig. 3 atfthe point. 20, the spring 18 and thedetent-arm do not offergreatre'sistance to the movement ofthe cam, and the parts may, therefore, be easily rota-ted for 'the purpose in question, by the application of a' force only slightly greater lthan that required to overcome the resistance ofthe spring l0, After each half-rotation of the parts, however, they lagain resume the position of Figl, in which they tend to come to rest, and thus the spring-tension may be increased' by a succession of half-ro-M To decrease .the

tations of the head 13. p springhtension thehead 13 is rotated in the opposite direction, asin Fig. 4. .At this time the' detent-arm is. also swung downwardly .i crum l cordingly, the resistance of the detentmech` by the cam, but the high points of the cam.

firs'tfengage the arm much nearer to its fulas. at the. `point 2l. in Fig. '4. Ac-

anism to rotation of the spring-shaft is substantlally greater in this` direction than in the opposite direction, being suiiicient` to `more than overoomethe rotative tendency of the spring 10. As the latter spring, how- -ever, .assists the operator in rotating the 4Uequlvalent arrangements may be employedl parts in this direction, thehead 13 may be easily .turned to decrease the tension, al-

though .securely held, when in the position ofFig.1. l y

g By theconstruction just described I produce a mechanism in which the manually-4 operable rotatable member 13 may be easily turned in either direction, according as it is required to increase or decrease the tension of the shutter-spring. While I preferably employ a cam and a resilient a'rm for this purpose, it will be understood that various for thispu-rpose, andthat the invention is not limited to the embodiment thereof specically described. i 1

'of the manually-operable member, said camsurface being formed to have a repressive action on the spring-pressed part in both' directions of rotation of the manually-operable member, so that said member may be l turned forcibly in either direction to increase or diminish the tension of the spring.

2, Spring-adjusting `mechanism having, in combination with a spring, `a manuallyrotatable member connected with the springto adjust the tension thereof, andldetent-v mechanism comprising a cam rotative with the manually-o erable member, and a nonrotative part aving a surface engaging the cam-surface,I one of said parts -bein spring-pressed'with a force suliicient to hold the cam normally against rotation, andone of said parts having a plurality of uniformly s aced projections, on its operative surface, ormed tohave a repressive action, on the spring-pressed art, in either.` direction of rotation of t e cam, .whereby a regularly fluctuating ,resistance to rotation 'of the manually-operable member 'in both directions is produced, while said member may be'forcibly rotated in either direction to increase or diminish the tensionof the 3. p'ring-adjusting' mechanism having, in combination with ai spring, a manuallyrotatable member connected with the spring to adjust the tension thereof, and'detentmechanism normally retaining said member in adjusted position, said mechanism comprising a cam rotative with said member, and aV resiliently-yielding part coperating with the cam, the cam having a high `pointI which engages said part with increased force so as to cause the manually-rotatable member to come to rest normally after'a predetermined degree of rotation.

.4. Spring-adjusting mechanism. having,

in combination with a spring,fa manuallyrotatable member connected with the spring to adjust the tension thereof, and detent mechanismy for retaining said member against rotation, said mechanism comprising a cam rotativewvith said member, and

a resilient swinging arm co erating with the cam, the cam having a hig point which lengages the arm, to swmg it, nearer to the center of movement of ther arm in one direction of rotation of the cam than in the other direction of rotation, whereby rotation of the earn is resisted more strongly 1n one direction than in the other.

5. Spring-adjusting mechanism having, in combination with. a spring, a 'manuallyrotatable member connected with the spring to adjust the tension thereof,` and detentmechanism normally retaining said member against rotation, said mechanism c0mprS- ing a substantially elliptical cam rotative with said member, a detent-arm pivoted on an axis parallel with the axis of the cam and having one side in engagement with the cam, and a second -spring connected with vthe arm and forcing it into such engagement.

G. Spring-adjusting mechanism having, in combination with a spring and with a fixed support, a manually-rotatable member connectedwith the spring to adjust the tension thereof, and detenta-mechanism normally retaining said member vin adjusted position, said mechanism` comprising two detent-members of which one is in the forniy member, to a rotative force greater than that normally sustained by the detent-members.

FARNUM F. DORSEY. Witnesses: l

D. GUnNEE, L. THON. 

